Sausage and Cheese Overnight Breakfast Casserole

This sausage and cheese overnight breakfast casserole is my family’s favorite for holiday mornings.

You assemble it the night before, let the bread soak up the custard, then bake until puffy and golden. It feeds a crowd and leaves you free to enjoy coffee instead of cooking.

What Makes This Casserole So Good

The top gets brown and crisp while the middle stays soft and custardy, almost like a savory bread pudding. A full pound of breakfast sausage and plenty of sharp cheddar mean every forkful is rich and hearty.

Because it sits overnight, the bread absorbs the egg mixture completely. In the morning you just slide the pan into the oven, and 45 minutes later a hot breakfast is ready with almost no work.

Ingredients

• 1 lb bulk pork breakfast sausage: mild or spicy both work, use your favorite.
• 1 loaf (1 lb) day-old French or Italian bread, cut into 1-inch cubes: slightly stale bread soaks up the custard without getting gummy.
• 8 oz sharp cheddar cheese, shredded: white or yellow cheddar, shredded off the block.
• 10 large eggs
• 3 cups whole milk: whole milk gives the richest custard, but 2% works in a pinch.
• 1 tsp kosher salt
• ½ tsp black pepper
• ½ tsp garlic powder
• 1 tbsp unsalted butter, for greasing the dish
• 2 tbsp sliced green onions, for serving: (optional)

Variations / Substitutions

• Swap the sausage: use cooked and crumbled bacon, diced ham, or a plant-based sausage crumble. Nothing else changes.
• Change the cheese: Gruyère, pepper jack, or a smoked cheddar all bring something a little different.
• Add vegetables: fold in 1 cup of sautéed mushrooms, spinach, or roasted red peppers when you layer the casserole.
• Make it dairy-free: use unsweetened oat milk and a good melting dairy-free cheese shred, though the custard may be slightly less rich.
• Go lighter: use turkey sausage and reduced-fat cheese, and replace half the milk with an unsweetened, unflavored plant milk.

If you like this one, give my cinnamon roll casserole a try when you want something sweet.

How to Make Overnight Breakfast Casserole

Step 1: Cook the Sausage

Heat a large skillet over medium-high heat. Add the 1 lb bulk sausage and cook, breaking it up with a wooden spoon, until browned and cooked through, about 8 minutes.

You want the sausage in small crumbles with plenty of crispy edges. When it is done, transfer it to a paper towel-lined plate to drain and cool.

Step 2: Assemble the Layers

Butter a 9×13-inch baking dish with the 1 tbsp butter. Spread half the bread cubes in an even layer, then scatter half the cooked sausage and half the shredded cheddar over the bread. Repeat with the remaining bread, sausage, and cheese.

As you build, you will see distinct ribbons of bread, meat, and cheese. Try to distribute everything evenly so each serving gets a little of everything.

Step 3: Whisk the Custard

In a large bowl or a 4-cup liquid measuring cup, whisk together the 10 eggs, 3 cups milk, 1 tsp salt, ½ tsp pepper, and ½ tsp garlic powder until smooth and no streaks of yolk remain. Slowly pour the custard all over the casserole, making sure to cover as much of the bread as possible.

You will see the bread begin to soak up the liquid right away. Use the back of a spatula to gently press the top layer of bread into the custard, helping it absorb. Cover tightly with plastic wrap and refrigerate for at least 8 hours, or up to 24.

Step 4: Bake the Casserole

When you are ready to bake, pull the dish from the fridge while the oven preheats. Heat the oven to 350°F (175°C). Remove the plastic wrap and let the dish sit on the counter for about 20 minutes while the oven comes to temperature. Bake, uncovered, for 45 to 50 minutes, until the top is puffed and deep golden brown and the center no longer jiggles.

The kitchen will fill with the smell of toasty bread and sausage. If the top is browning too fast before the center sets, loosely tent a piece of foil over it for the last 15 minutes.

Step 5: Slice and Serve

Let the casserole rest for 5 minutes on a cooling rack. Slice it into squares right in the dish and use a wide spatula to lift each portion out. Sprinkle the green onions over the top, if using.

Each square holds together with a crisp, golden top and a tender, custardy base that barely needs a fork.

Tips for a Perfect Breakfast Casserole

• Use day-old bread. Fresh, soft bread can turn mushy during the long soak. If your bread is fresh, spread the cubes on a sheet pan and dry them in a 300°F oven for 10 minutes, then cool.
• Don’t skip the overnight rest. The long soak lets the custard fully penetrate the bread, so you get a uniform texture instead of dry pockets.
• Let the casserole sit at room temperature before baking. Pulling it from the fridge 20 minutes early helps it heat through more evenly.
• Tent with foil if needed. Ovens vary, so if the top is already deep brown around 35 minutes, cover it loosely to finish baking without burning.
• Customize the mix-ins. Just keep the total volume of add-ins similar (about 2 to 3 cups) so the custard ratio stays balanced.

Bake times by pan size:

Pan size	Bake time at 350°F
8×8 inches	35–40 minutes
9×13 inches	45–50 minutes
11×13 inches	40–45 minutes

Storing Leftovers

Cover leftover squares tightly and refrigerate for up to 4 days. Reheat individual portions in the microwave for about 1 minute, or warm larger pieces in a 325°F oven for 10 to 15 minutes until heated through.

What to Serve with This Casserole

A pile of fresh fruit balances the richness with something bright and cool. I like a bowl of mixed berries or citrus slices. For something green, a simple arugula salad with lemon vinaigrette cuts through the richness without adding weight. Roasted breakfast potatoes or a side of crispy hash browns make it even heartier, though the casserole is plenty on its own.

Frequently Asked Questions

Can I freeze the unbaked casserole?

No, the long soak in the fridge is enough. Freezing changes the custard texture and leads to a watery bake. Bake it first, then freeze cooled portions for up to 2 months.

Why did my casserole turn out dry?

It likely overbaked. Pull it from the oven as soon as the center is set and no longer liquid, even if the top looks slightly pale. Carryover cooking will finish it.

Can I use whole wheat bread?

Yes, but the texture will be denser and the flavor earthier. Day-old sturdy whole wheat or multigrain bread works, though the casserole may be less airy than with white bread.

My top is browning too fast. Help?

Lay a sheet of foil loosely over the top for the last 15 to 20 minutes of baking. The foil reflects heat away from the surface while the middle finishes setting.